• 대한기계학회논문집A
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• 제30권6호
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• pp.670-677
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• 2006

Vacuum interrupters are used in various switch-gear components such as circuit breakers, distribution switches, contactors. The electrodes of a vacuum interrupter are manufactured of sinter-forged Cu-Cr material for good electrical and mechanical characteristics. Since the closing velocity is 1-2m/s and impact deformation of the electrode depends on the strain-rate at the given velocity, the dynamic material property of the sinter-forged Cu-Cr alloy is important to design the vacuum interrupter reliably and to identify the impact characteristics of a vacuum interrupter accurately. This paper is concerned with the dynamic material properties of sinter-forged Cu-Cr alloy for various strain rates. The amount of chrome is varied from 10 wt% to 30 wt% in order to investigate the influence of the chrome content on the dynamic material property. The high speed tensile test machine is utilized in order to identify the dynamic property of the Cu-Cr alloy at the intermediate strain-rate and the split Hopkinson pressure bar is used at the high strain-rate. Experimental results from both the quasi-static and the high strain-rate up to the 5000/sec are interpolated with respect to the amount of chrome in order to construct the Johnson-Cook and the modified Johnson-Cook model as the constitutive relation that should be applied to numerical simulation of the impact behavior of electrodes.

• Asian-Australasian Journal of Animal Sciences
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• 제18권6호
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• pp.780-786
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• 2005

This study presents a non-video, non-invasive, automatic, on-site monitoring system the system employs ultrasonic transducers to detect behavior in sows before, during and after parturition. An ultrasonic transmitting/receiving (T/R) circuit of 40 kHz was mounted above a conventional parturition bed. The T/R units use ultrasonic time-of-flight (TOF) ranging technology to measure the height of the confined sows at eight predetermined locations. From this data, three momentary postures of the sow are determined, characterized as standing-posture (SP), lateral-lying-posture (LLP) and sitting posture (STP). By examining the frequencies of position switch Stand-Up-Sequence (SUS) between standing-posture (SP), lateral-lying-posture (LLP) and sitting-posture (STP) rate can be determined for the duration of the sow' confinement. Three experimental pureblooded Landrace sows undergoing normal gestation were monitored for the duration of confinement. In agreement with common observation, the sows exhibited increased restlessness as parturition approached. Analysis of the data collected in our study showed a distinct peak in Stand-Up-Sequence (SUS, i.e. the transition from lying laterally to standing up ) and sitting-posture (STP) rate approximately 12 h prior to parturition, the observed peak being 5 to 10 times higher than observed on any other measurement day. It is concluded that the presented methodology is a robust, low-cost, lowlabor method for the continuous remote monitoring of sows and similar large animals for parturition and other behavior. It is suggested that the system could be applied to automatic prediction of sow parturition, with automatic notification of remote management personnel so human attendance at birth could reduce rates of sow and piglet mortality. The results of this study provide a good basis for enhancing automation and reducing costs in large-scale sow husbandry and have applications in the testing of various large mammals for the effects of medications, diets, genetic modifications and environmental factors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1034-1035
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• 2015

Watertight 25.8 kV/600 A/12.5 kA fault current limiters (FCLs) have successfully installed in five areas (Incheon, Seoul, Gyeong-gi, Daejeon, Suwon) on KEPCO power distribution line for the purpose of commercial demonstrations. The fault current limiting operation of this FCL, which includes functions of sensing, commutation, and reduction of fault currents, is perfectly completed within 1 cycle immediately after fault occurs. The performance of FCL was verified by short circuit test, impedance test, insulation test, temperature-rise test, and control test, etc at PT&T in LS industrial systems, which is the official certification institute in Korea. In 2013, and also the FCL field test was performed in order to test the protection coordination between conventional relays and FCL, on the 1.5 kA and 5.0 kA faults, which were made by connecting the Artificial Fault Generator (AFG) to the distribution line in test grid at KEPCO Power Testing Center. The next step of this project is to check the FCL conditions caused by real external environment, and acquire the various data from five regions installed with FCL. In this paper, we intend to explain the FCL specifications and performance characteristics, and check the expected effect by application of FCL to power distribution line based on the power system analysis of an application site.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.178-178
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• 2010

With the scaling down of ULSI(Ultra Large Scale Integration) circuit of CMOS(Complementary Metal Oxide Semiconductor)based electronic devices, the electronic devices become more faster and smaller size that are promising field of semiconductor market. However, very narrow line width has some disadvantages. For example, because of narrow line width, deposition of conformal and thin barrier is difficult. Besides, proportion of barrier width is large, thus resistance is high. Conventional PVD(Physical Vapor Deposition) thin films are not able to gain a good quality and conformal layer. Hence, in order to get over these side effects, deposition of thin layer used of ALD(Atomic Layer Deposition) is important factor. Furthermore, it is essential that copper atomic diffusion into dielectric layer such as silicon oxide and hafnium oxide. If copper line is not surrounded by diffusion barrier, it cause the leakage current and devices degradation. There are some possible methods for improving the these secondary effects. In this study, TaNx, is used of Tertiarybutylimido tris (ethylamethlamino) tantalum (TBITEMAT), was deposited on the 24nm sized trench silicon oxide/silicon bi-layer substrate with good step coverage and high quality film using plasma enhanced atomic layer deposition (PEALD). And then copper was deposited on TaNx barrier using same deposition method. The thickness of TaNx was 4~5 nm. TaNx film was deposited the condition of under $300^{\circ}C$ and copper deposition temperature was under $120^{\circ}C$, and feeding time of TaNx and copper were 5 seconds and 5 seconds, relatively. Purge time of TaNx and copper films were 10 seconds and 6 seconds, relatively. XRD, TEM, AFM, I-V measurement(for testing leakage current and stability) were used to analyze this work. With this work, thin barrier layer(4~5nm) with deposited PEALD has good step coverage and good thermal stability. So the barrier properties of PEALD TaNx film are desirable for copper interconnection.

• 대한전자공학회논문지
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• 제25권9호
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• pp.1115-1124
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• 1988

A two-dimensional systolic array for fast Fourier transform, which has a regular and recursive VLSI architecture is presented. The array is constructed with identical processing elements (PE) in mesh type, and due to its modularity, it can be expanded to an arbitrary size. A processing element consists of two data routing units, a butterfly arithmetic unit and a simple control unit. The array computes FFT through three procedures` I/O pipelining, data shuffling and butterfly arithmetic. By utilizing parallelism, pipelining and local communication geometry during data movement, the two-dimensional systolic array eliminates global and irregular commutation problems, which have been a limiting factor in VLSI implementation of FFT processor. The systolic array executes a half butterfly arithmetic based on a distributed arithmetic that can carry out multiplication with only adders. Also, the systolic array provides 100% PE activity, i.e., none of the PEs are idle at any time. A chip for half butterfly arithmetic, which consists of two BLC adders and registers, has been fabricated using a 3-um single metal P-well CMOS technology. With the half butterfly arithmetic execution time of about 500 ns which has been obtained b critical path delay simulation, totla FFT execution time for 1024 points is estimated about 16.6 us at clock frequency of 20MHz. A one-PE chip expnsible to anly size of array is being fabricated using a 2-um, double metal, P-well CMOS process. The chip was layouted using standard cell library and macrocell of BLC adder with the aid of auto-routing software. It consists of around 6000 transistors and 68 I/O pads on 3.4x2.8mm\ulcornerarea. A built-i self-testing circuit, BILBO (Built-In Logic Block Observation), was employed at the expense of 3% hardware overhead.

• 전자공학회논문지SC
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• 제49권1호
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• pp.80-87
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• 2012

본 논문에서는 열상장비의 광 검출기에서 검출된 미약한 전기적 신호를 영상신호처리를 하기 위한 신호로 증폭을 해 주는 전단 증폭부의 성능 검사용 ATE(Automatic Test Equipment)를 개발하였다. 기존 ATE 장비는 주로 반도체 소자 양품검사 분야에서 활발히 개발되고 있었으나 최근에는 장비의 성능검사 분야에서도 연구되고 있다. 그러나 열상장비 성능검사 분야의 ATE 에 대한 연구는 다른 분야에 비해 미진하여 우리군의 핵심적인 감시 장비인 열상장비는 정비가 제한되었다. 이에 따라 본 논문에서는 새로운 열상장비 분야의 ATE 연구가 필요하여 전단증폭부 및 열상장비의 다른 회로카드의 범용적인 개발이 가능하도록 Matrix Relay를 개발하였다. 개발된 ATE로 전단증폭부의 증폭도를 측정한 결과 증폭 전압은 평균 2.71 Vpp로써 이론적인 분석 범위 내에 있음이 확인되어 개발된 ATE가 우수한 성능임이 검증되었다.

• Carbon letters
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• 제21권
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• pp.68-73
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• 2017

We have demonstrated the production of thin films containing multilayer graphene-coated copper nanoparticles (MGCNs) by a commercial electrodeposition method. The MGCNs were produced by electrical wire explosion, an easily applied technique for creating hybrid metal nanoparticles. The nanoparticles had average diameters of 10-120 nm and quasi-spherical morphologies. We made a complex-electrodeposited copper thin film (CETF) with a thickness of $4.8{\mu}m$ by adding 300 ppm MGCNs to the electrolyte solution and performing electrodeposition. We measured the electric properties and performed corrosion testing of the CETF. Raman spectroscopy was used to measure the bonding characteristics and estimate the number of layers in the graphene films. The resistivity of the bare-electrodeposited copper thin film (BETF) was $2.092{\times}10^{-6}{\Omega}{\cdot}cm$, and the resistivity of the CETF after the addition of 300 ppm MGCNs was decreased by 2% to ${\sim}2.049{\times}10^{-6}{\Omega}{\cdot}cm$. The corrosion resistance of the BETF was $9.306{\Omega}$, while that of the CETF was increased to 20.04 Ω. Therefore, the CETF with MGCNs can be used in interconnection circuits for printed circuit boards or semiconductor devices on the basis of its low resistivity and high corrosion resistance.

• 한국의학물리학회지:의학물리
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• 제26권2호
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• pp.99-105
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• 2015

모니터 전리함은 의료용 선형가속기에서 방출되는 방사선의 세기와 출력 제어를 위하여 사용된다. 본 연구에서는 가속기 기반 방사선 발생장치의 제어 시스템 개발에 사용하기 위하여 모니터 전리함 시작품을 개발하였다. 개발한 모니터 전리함은 평행 평판형 전리함 형태로서 독립적 작동이 가능한 두 개의 전리함으로 구성되어 있으며, 전극의 재료는 방사선의 감쇠를 최소화하기 위하여 얇은 연성인쇄회로기판이 사용되었다. 전리함의 시험을 위하여 코발트-60 방사선원을 이용하여 측정된 전하의 포화특성과 선형성과 같은 선량학적 특성을 평가하였다. 결과적으로 개발된 시작품이 기본 성능을 만족하며 추가 연구의 가능성을 확인하였다.

• Annals of Clinical Neurophysiology
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• 제14권2호
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• pp.64-71
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• 2012

Background: It is generally accepted that upper motor neuron (UMN) lesion can alter lower motor neuron (LMN) function by the plasticity of neural circuit. However there have been only few researches regarding the axonal excitability of LMN after UMN injury especially during the acute stage. The aim of this study was to investigate the nerve excitability properties of the LMNs following an acute to subacute supratentorial corticospinal tract lesion. Methods: An automated nerve excitability test (NET) using the threshold tracking technique was utilized to measure multiple excitability indices in median motor axons of 15 stroke patients and 20 controls. Testing of both paretic and non-paretic side was repeated twice, during the acute stage and subacute stage. The protocols calculated the strength-duration time constant from the duration-charge curve, parameters of threshold electrotonus (TE), the current-threshold relationship from sequential sub-threshold current, and the recovery cycle from sequential supra-threshold stimulation. Results: On the paretic side, compared with the control group, significant decline of superexcitablity and increase in the relative refractory period were observed during the subacute stage of stroke. Additionally, despite the absence of statistical significance, a mildly collapsing in ('fanning in') of the TE was found. Conclusions: Our results suggest that supratentorial brain lesions can affect peripheral axonal excitability even during the early stage. The NET pattern probably suggests background membrane depolarization of LMNs. These features could be associated with trans-synaptic regulation of UMNs to LMNs as one of the "neural plasticity" mechanisms in acute brain injury.

• 한국전자통신학회논문지
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• 제13권4호
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• pp.757-764
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• 2018

본 논문은 공조시스템에 사용되는 1마력급 2상 BLDC 팬모터의 설계 및 구현에 관하여 기술한다. 본 연구에서 구현한 BLDC 모터는 수명 및 내구성이 우수한 무정류자 모터방식이며 2상 전원에 의해 구동된다. 공조시스템에 사용되는 모터의 가장 중요한 목표사양은 정격운전점에서 높은 효율을 갖는 것이다. 이를 위해 BLDC 모터의 고정자 형상과 회전자 자석의 설계를 수행하고 구동을 위한 제어회로를 설계하였다. BLDC 모터는 모터부와 제어부 그리고 전원부가 일체화된 구조를 갖는다. BLDC 모터의 특성계산을 위해 유한요소해석을 사용하였으며 시제품의 제작 및 성능시험을 실시하여 설계결과의 적합성을 확인하였다.